Portland State University campus police shot and killed a man outside the Cheerful Tortoise, a downtown bar, early Friday morning.
Cell phone video published by KPTV shows at least one man yell "Drop the gun," before police fired multiple shots.
A bystander interviewed by the TV station told a reporter that the man had been attempting to break up a fight that involved an armed person outside the bar around 1:30 a.m.
"It just took a turn for the worst and the good guy ended up getting shot," she said.
Emergency medical responders declared the man dead at the scene.
Portland police are investigating the shooting and have not yet identified the man killed or the officers who fired their weapons.
PSU decided to arm its campus police force in 2016, a controversial choice that drew protests from students.
The shooting comes just over a month after a man drove his car onto the sidewalk, hitting and injuring three women on the PSU campus.